Stereoscopic imaging, or three dimensional imaging, allows for the viewing of three dimensional information, including imagery depth and special details, from two or more two-dimensional displays or images. Stereoscopic imaging is typically accomplished by presenting a slightly different image to each eye of the viewer, to thereby capture the imagery depth and spatial details. This can be done in a number of different ways, including the display assembly of FIG. 1 described below.
FIG. 1 depicts a typical stereographic display assembly 100, known in the art, for displaying stereographic or stereoscopic images. The stereographic display assembly 100 includes a first display 102, a second display 104, and a beamsplitter 106, along with optional eyewear 108. The beamsplitter 106 includes an external mirror 110 which is partially reflective and partially transmissive. The first display 102 and the second display 104 display a first image and a second image, respectively, and the beamsplitter 106 overlays the two displayed images, to thereby provide depth perception and a three dimensional viewing experience.
The stereographic display assembly 100, and similar stereographic devices, can be effective in displaying stereographic images, and can result in improvements in performing various tasks, among various other potential benefits. However, the depicted stereographic display assembly 100, and other stereographic devices, can also lead to some less than optimal results. For example, refraction from the beamsplitter 106 can divert the line of sight from one of the two displays 102 or 104, thereby resulting in what is sometimes referred to as “dipvergence”.
Dipvergence occurs when, as shown in FIG. 1, the line of sight for the second display 104 is shifted vertically, relative to the line of sight for the matching portion of the first display 102, by one or more delta values 112. This dipvergence can result in viewer fatigue and discomfort, and can potentially interfere with the benefits of using a stereographic display assembly. Additionally, the delta values 112 typically vary at different points along the second display 104 as well as with different vantage points or positions for viewing the display. For example, and, as also shown in FIG. 1, a first delta value 112(A) near the top of the second display 104 may be larger than a second delta value 112(B) near the bottom of the second display 104. Accordingly, a first order vertical shift would not resolve the dipvergence problem. Positioning the mirror 110 on the opposite side of the beamsplitter 106 would alter the diagram somewhat, but would also not resolve the dipvergence problem. Moreover, in high vibration environments such as aircraft, thicker beamsplitters 106 may be used, which can lead to increased dipvergence, particularly in stereographic display assemblies in which the beamsplitter 106 is a relatively short distance from the first and second displays 102, 104.
Accordingly, it is desirable to have an improved stereographic device for three dimensional viewing with decreased dipvergence, and preferably with decreased dipvergence through the entire displays. It is also desirable to have such an improved stereographic device that can be used in high vibration environments such as aircraft, for example with a relatively thick beamsplitter, and with stereographic display assemblies in which the beamsplitter is a relatively short distance from the displays. The present invention addresses one or more of these needs. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.